I have a 2005 chevy Silverado 2500hd with 40,000 mile and it keeps throwing a p0300 random misfire . what could be the problem

 

I have just bought the truck and everytime I bring the truck to him to get it fixed I tell him that the injectors need to be replaced but he just has his mechanics put new coils in and plugs and wires but overtime I pick it up the light just pops back on once I hit like 60 mph

 

I wouldn't be thinking fuel injectors here just yet.

Any shop or person that is worth a salt will be using some of diag tool to hopefully figure out the issue. P0300 means more than one cylinder has the issue. If you can watch the scanner to pinpoint which cylinders it is, then it's easier to figure out the next steps.

If plugs and wires didn't help, then swapping injectors around could be done to see if the misfire jumps cylinders. Also the scan tool could be helpful to see what o2 sensors are doing, what MAP and MAF sensor data is like, to make sure they are within spec. They should also be testing fuel pressure as well to make sure that is not falling off.